Role of Fibre in Reinforcement of Structure During Earthquake

Transcription

1 Role of Fibre in Reinforcement of Structure During Earthquake Fibre Reinforcement, Earthquake and Structure failure Ms. Chhavi Gupta* Technical Skill Refinement Program (TSRP) Feb. 04, 2017 Department Of Civil Engineering

2 Contents 1. Motivation 2. Introduction 3. Efforts to reduce failures 4. Experimental studies 5. Challenges Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 1

3 Motivation The fifth revision of IS 1893 has brought more than fifty percent of the country under moderate and severe seismic zones. Reasons of structure failure from earthquake studies: 1. Breakdown of corners joint 2. Base Isolation 3. Rigidity of structure Focus on Breakdown of Corners Joint The times of India Subodh Varma TNN May 1, 2015 Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 2

4 Introduction What is the behavior of structure During earthquake? In a moment resistant frame, three types of joints can be identified as: Seismic loading on interior joint forces on exterior joint Corner joint Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 3

5 Introduction Corner joint- 1. Bending moment which tend to close the corner. 2. Bending moment which tend to open the corner. Closing joint (top view) Opening joint (top view) Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 4

6 Introduction CASE 1: Bending moment which tend to close the corner Concern: Anchorage of reinforcement is a serious problem in case of closing corner. CASE 2: Bending moment which tend to open the corner. Concern: The diagonal resultant is tensile, that is a serious problem. We focus on Case 2 Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 5

7 Efforts to reduce the failures Nilsson, I.H.E. (1973) 1 Indian Standards (1987), (1997) 3 Noor, F.A. (1977) 2 Efficiencies close to 100% were obtained Past Efforts Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 6

8 Efforts to reduce the failure Issues- Available space in joint is limited. Major role- Fibre can play major role as fibred reinforced concrete with simple detailing system so efficiency can be increased. RCC beam with fibre during load Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 7

9 Experimental and Analytical study 1. The efficiency of detailing systemsp1 was found to be 70.33% 2. The efficiency of this detailing system SP2 was obtained as 95.33% Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 8

10 Experimental and Analytical study Loading Arrangement: 1. Jack and a pump unit. 2. A pair of stiff mild steel bearing plate mm diameter mild steel roller 4. Cover plate 5. The bearing plate as a point 6. Two 6 mm diameter mild steel runners 7. Proving ring of 50 KN capacity Loading Arrangement Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 10

11 Experimental and Analytical study Fibre Reinforced Portion Loading Arrangement of Specimen Portion of frame(corners), where steel fibres are provided Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 9

12 Experimental and Analytical study With the addition of0.5%, 1%, 1.5%, 2% volume fraction of fibres in SP2, The ultimate load carrying capacity of joint improved by 9.91%, 31.65%, 42.86% and 18.95% respectively as compared to specimen without fibres (SP2). Specimen Ultimate Load (KN) Experimental Analytical Percentage error First Crack SP2A SP2B SP2C SP2D SP1 SP2 SP2A SP2B SP2C SP2D SP1 SP2 SP2A SP2B SP2C SP2D Comparison of Ultimate Load for fibrous specimens Efficiency of Specimens Load verses first crack value Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 11

13 Experimental and Analytical study SP1=DETAILING SYSTEM1 SP2= DETAILING SYSTEM 2 SP2A = D.S 2 WITH 0.5% FIBRE SP 2B = D.S 2 WITH 1% FIBRE SP2C = D.S 2 WITH 1.5% FIBRE SP2D = D.S 2 WITH 2% FIBRE D.S =DETAILING SYSTEM Load-Deflection behaviour of SP1, SP2, SP2A,SP2B, SP2C and SP2D Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 12

14 Experimental and Analytical study SP1=DETAILING SYSTEM1 SP2= DETAILING SYSTEM 2 SP2A = D.S 2 WITH 0.5% FIBRE SP 2B = D.S 2 WITH 1% FIBRE SP2C = D.S 2 WITH 1.5% FIBRE SP2D = D.S 2 WITH 2% FIBRE D.S =DETAILING SYSTEM Moment-Rotation behaviour of SP1, SP2, SP2A, SP2B, SP2C and SP2D Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 13

15 Challenges After 1.5 and 2 percentage of steel fibre, balling effect decreases the strength and efficiency of fibre reinforcement concrete member. Balling effect A collection of long thin steel fibres, usually with aspect ratio higher than 100, will interlock to form a mat, or a ball, during mixing. Once these balls have formed, separating the fibres is extremely difficult. Bond is one of the reasons why straight smooth fibres cannot be successfully used in the field. Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 14

16 References 1. Nilsson, I.H.E. (1973), Reinforced Concrete Corners and Joints Subjected to Bending Moment-Design of Corners and joints in frame Structures, National Swedish Institute for Building Research, Stockholm, Document No.D Noor, F.A. (1977), Ultimate Strength and Cracking of Wall Corners, Concrete, V.11, No.7, July, pp SP 34:1987 (1997), Handbook on Concrete Reinforcement and Detailing, Bureau of Indian Standards, New Delhi. Feb. 04, 2017, Gupta, C. G. Fibre Reinforcement, Earthquake and Structure failure 15

17 THANK YOU Special Thanks: Prof. Roshan Lal, PEC University of Technology India. Thanks to Colleagues: Dr. Satyaprakash, Dr. Prabhas Yadav and Civil Engineering Department.